Actuation system for at least one hydraulically actuatable device, in particular a vehicle brake

Abstract

An actuation system for at least one hydraulically actuatable device, e.g., a vehicle brake, may include an actuation device, e.g., a brake pedal, at least one first pressure source that can be actuated using the actuation device, and a second pressure source having a pressure-generating arrangement that is moveable in two directions, and which includes an electro-mechanical drive for the pressure-generating arrangement. Each pressure source is connected via at least one hydraulic line to the hydraulically actuatable device for supplying pressurising medium. A valve device may regulate pressure of the hydraulically actuatable device. Pressurising medium can be supplied in a controlled manner in both movement directions of the pressure-generating arrangement. Provision is made for two working chambers of the second pressure source to be connected by a hydraulic line, and a valve device may be arranged in the hydraulic line.

What is claimed is: 
     
       1. An actuation system for at least one hydraulically actuatable device, comprising:
 an actuation device, 
 at least one first pressure source configured to be actuated using the actuation device and 
 a second pressure source, including:
 a first working chamber and a second working chamber; 
 a pressure-generating organ that is moveable in two directions, wherein the pressure-generating organ includes a piston, and 
 an electro-mechanical drive for driving the pressure-generating organ, 
 
 wherein the at least one first pressure source is connected via at least one first hydraulic line and the second pressure source is connected via at least a second hydraulic line and at least a third hydraulic line to the hydraulically actuatable device in order to supply the at least one first pressure source and the second pressure source with pressurizing medium or to pressurize them, and 
 a valve arrangement for regulating the pressure of the hydraulically actuatable device, wherein pressurizing medium is enabled to be supplied in a controlled manner by means of the second pressure source in both movement directions of the pressure-generating organ, 
 a fourth hydraulic line, which does not overlap with the second hydraulic line and does not overlap with the third hydraulic line, that leads from the second working chamber to a reservoir; 
 a switching valve arranged in the fourth hydraulic line, 
 wherein the actuation system is configured to 
 a) move the piston of the second pressure source in a forward position; and 
 b) initiate a return stroke of the piston during which the switching valve is open such that pressurizing medium is moved from the hydraulically actuatable device into the first working chamber for pressure reduction. 
 
     
     
       2. The actuation system according to  claim 1 , wherein a switching valve is arranged in at least one of the second or third hydraulic lines connecting the second pressure source to the actuatable device. 
     
     
       3. The actuation system according to  claim 1 , wherein the first pressure source comprises a first working chamber with a first piston and a second working chamber with a second piston. 
     
     
       4. The actuation system according to  claim 3 , wherein each working chamber of the first pressure source is connected via the at least one first hydraulic line to the hydraulically actuatable device. 
     
     
       5. The actuation system according to  claim 1 , wherein a switching valve is arranged in at least one of the hydraulic lines connecting the first pressure source to the actuatable device. 
     
     
       6. The actuation system according to  claim 1 , wherein the first pressure source is a first piston-cylinder unit that serves as a master cylinder of a vehicle brake. 
     
     
       7. The actuation system according to  claim 1 , further comprising a hydraulic path simulator that is operatively connected to a working space of the first pressure source. 
     
     
       8. The actuation system according to  claim 1 , comprising a first brake circuit and a second brake circuit, wherein the first brake circuit comprises the second hydraulic line and the second brake circuit comprises the third hydraulic line. 
     
     
       9. The actuation system according to  claim 8 , wherein the second brake circuit comprises separate intake valves and exhaust valves, wherein the exhaust valves are arranged in a return line which leads to the reservoir. 
     
     
       10. The actuation system according to  claim 8 , wherein the first brake circuit comprises a valve assigned to a first wheel brake and a valve assigned to a second wheel brake. 
     
     
       11. The actuation system according to  claim 1 , wherein a switching valve is arranged in a connecting line that connects the second and the third lines. 
     
     
       12. The actuation system according to  claim 1 , further comprising at least one switching valve for connecting the first and second working chambers of the second pressure source and/or for connecting the second and third hydraulic line. 
     
     
       13. The actuation system according to  claim 1 , further comprising a hydraulic connecting line disposed between the fourth hydraulic line and the first working chamber, wherein the switching valve is disposed between the second working chamber and the hydraulic connecting line. 
     
     
       14. The actuation system according to  claim 13 , further comprising a non-return valve disposed in the hydraulic connecting line and arranged to permit pressurizing medium to flow into the first working chamber. 
     
     
       15. A method for operating a brake actuation system, wherein a first pressure source is configured to be actuated by an actuation device and coupled via a first hydraulic line to at least two hydraulic circuits, and wherein a second pressure source is allocated to the at least two hydraulic circuits via at least a second hydraulic line and at least a third hydraulic line in order to supply the second and third hydraulic lines with pressurizing medium, the second pressure source including:
 a first working chamber and a second working chamber; 
 a piston that is moveable in two directions, and 
 an electro-mechanical drive for driving the piston, 
 
       wherein the second pressure source conveys pressurizing medium in two delivery directions, wherein the actuation system further comprises:
 a fourth hydraulic line, which does not overlap with the second hydraulic line and does not overlap with the third hydraulic line, that leads from the second working chamber to a reservoir; and 
 a switching valve arranged in the fourth hydraulic line, 
 wherein the method comprises: 
 a) moving the piston of the pressure source in a forward position; and 
 b) after moving the piston of the pressure source in the forward position, initiating a return stroke of the piston during which the switching valve is open such that pressurizing medium is moved from at least one of the hydraulic circuits into the first working chamber for pressure reduction in the at least one of the hydraulic circuits. 
 
     
     
       16. The method according to  claim 15 , wherein during the return stroke of the piston of the pressure source, pressurizing medium is moved into the first working chamber via a hydraulic connecting line connecting the third hydraulic line and the first working chamber. 
     
     
       17. The method according to  claim 16 , wherein a non-return valve disposed in the hydraulic connecting line permits pressurizing medium to flow into the first working chamber.